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Thulium (Tm)
We are a leading manufacturer and supplier of research materials
Thulium 69Tm168.93421
Discovered in 1879 by P.T. Cleve at Uppsala, Sweden.
[Called after Thule, an ancient name for Scandinavia]
French: thulium
German: Thulium
Italian: tulio
Spanish: tulio
Description: Thulium is a silvery metal, and rarest of the so-called rare earth group (more correctly termed the lanthanides). It tarnished in air and reacts with water. Thulium has few uses but some is employed as a radiation source in portable X-ray equipment.
Further Materials properties
| Crystal structure: |
(cell dimensions/pm), space group, |
|---|---|
| X-ray diffractions mass absorption coefficients: | CuKa 140 (µ/r) / cm2g-1 MoKa 80.8 (µ/r) / cm2g-1 |
| Neutron scattering length: | 0.707 b/10-12 cm |
| Thermal neutron capture cross-section: | 100 sa / barns |
| Density: | 9321 kg/m-3 [293 K] |
| Melting point: | 1544.85°C / 1818°K |
| Boiling point: | 1946.85°C / 2220°K |
| Molar volume: | 18.12 cm3 |
| Thermal conductivity: | 16.8 [300 K] W m-1K-1 |
| Coefficient of linear thermal expansion: | 13.3 x 10-6 K-1 |
| Electrical resistivity: | 79.0 x 10-8 [295 K] Ωm |
| Mass magnetic susceptibility: | +1.90 x 10-6(s) kg-1m3 |
| Radi: | Tm4+ 87; Tm3+ 94; atomic 175; covalent 156 |
| Electronegativity: | 1.25 (Pauling); 1.11 (Allred); ≤3.4 eV (absolute) |
| Effective nuclear charge: | 2.85 (Slater); 8.58 (Clementi); 11.80 (Froese-Fischer) |
| Number of Isotopes (incl. nuclear isomers): | 28 |
| Isotope mass range: | 152 -> 176 |
Biological data
| Biological role: | None, but acts to stimulate metabolism. |
|---|---|
| Toxicity | |
| Toxic intake: | n.a. |
| Lethal intake: | LD50 (chloride, oral, mouse) = 4290 mg Kg-1 |
| Hazards: | Thulium is mildly toxic by ingestion. |
| Level in humans | |
| Organs: | n.a., but low |
| Daily dietary intake: | n.a. |
| Total mass of element in average [70 kg] person: |
n.a. |
Geological data
| Minerals: | ||||
|---|---|---|---|---|
| Mineral | Formula | Density | Hardness | Crystal apperance |
| Bastnäsite* | (Ce, La, etc.) CO3F | 4.9 | 4 - 4.5 | hex., vit/ greasy yellow |
| Monazite* | (Ce, La, Nd, Th, etc.)PO4 | 5.20 | 5 - 5.5 | mon., waxy/ vit. yellow-brown |
* although not a major constituent, thulium is present in extractable amounts.
| Chief ores: | monazite, bastnäsite |
|---|---|
| World production: | c. 50 tonnes/year |
| Main mining areas: | USA, Brazil, India, Sri Lanka, Australia |
| Reserves: | c. 1 x 105 tonnes |
| Specimen: | available as chips, ingots or powder. |
| Abundances | |
|---|---|
| Sun: | 1.8 (relative to H = 1 x 1012) |
| Earth's crust: | 0.48 ppm |
| Seawater | |
| Altantic surface: | 1.3 x 10-7 |
| Atlantic deep: | 1.6 x 10-7 |
| Pacific surface: | 0.7 x 10-7 |
| Pacific deep: | 3.3 x 10-7 |
| Residence time: | n.a. |
| Classification: | recycled |
| Oxidation state: | III |
Source: Emsley, J. (1998) The Elements (3rd Edition)
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